AU597852B2 - Process for preparing positive and negative images using photohardenable electrostatic master - Google Patents

Description

r -cr it:

I

1 1 59 7 852 AUSTRALIA Form PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Short Title: Int. CI: ,pplication Number: e Lodged: Complete Specification-Lodged: Accepted: r Lapsed: Published: TIM ducument c0ntai& t'3e amendments made under Section 49.

and 12 corrct: for printtn

J

Priority: Related Art: Lt t t Name of Applicant: Address of Applicant: TO BE COMPLETED BY APPLICANT E. I. DU PONT DE NEMOURS COMPANY 10007 MARKET STREET

-WILMINGTON

DELAWARE, 19898

U.S.A.

Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: PROCESS FOR PREPARING POSITIVE AND NEGATIVE IMAGES USING PHOTOHARDENABLE ELECTROSTATIC MASTER The following statement is a full description of this invention, including the best method of performing it known to me:- PF/CP1F/2/80 1 I1 TITLE IM-0059 PROCESS FOR PREPARING POSITIVE AND NEGATIVE IMAGES USING PHOTOHARDENABLE ELECTROSTATIC MASTER

DESCRIPTION

TECHNICAL

FIELD

This invention relates to an electrostatic process for producing images using a photohardenable electrostatic master. More particularly this invention relates to an electrostatic process for 1 producing multiple positive or negative images using a photohardenable electrostatic master comprising an S, electrically conductive support bearing a f photohardenable composition comprising a polymeric binder, ethylenically unsaturated compound 15 photoinitiator, photoinhibitor and a sensitizer *fi t compound.

t Z BACKGROUND OF THE INVENTION Photopolymerizable (photohardenable) compositions and films containing binder, monomer, initiator and chain transfer agent are described in the prior art and sold commercially. One important 0 application of photopolymerizable layers is in graphic arts. Photopolymerizable layers on conductive supports currently may be used as Selectrostatic masters for analog color proofing and are considered as promising future materials to be developed for digital color proofing applications.

For the analog color proofing application, a photopolymer layer is coated on an electrically conductive substrate and contact exposed with an ultraviolet (UV) source through a half tone color separation negative. The photopolymer hardens in the areas exposed with an ultraviolet source due to polymerization and remains in a softer state l/ t I N 2 elsewhere. The differences in viscosity between the exposed and unexposed areas are apparent in the transport properties, the unexposed photopolymer conducts more electrostatic charge while the UV exposed areas are substantially nonconductive. By subjecting the exposed photopolymer layer to a corona discharge a latent electrostatic image is obtained consisting of electrostatic charge remaining only in the nonconducting or exposed areas of the photopolymer layer. This latent image can then be developed by application of a liquid electrostatic toner to the surface. When the developer has the opposite charge as the corona charge, the developer selectively S° "15 adheres to the exposed or polymerized areas of the .44: photopolymer layer. The developer in the exposed areas subsequently can be transferred to a surface such as paper to produce an image. The photohardenable electrostatic master described is *4 20 negative working. Color proofs can be prepared by repeating the procedure using other photopolymer masters, imagewise exposing each master through a different color transparency, corona charging, developing each exposed master with a correspondingly colored developer, and transferring each developed 4* image sequentially in register on the preceding transferred image.

Dueber U.S. Patent 4,162.162 describes certain photopolymerizable compositions which in addition to the basic constituents for a photohardenable composition contain a visible sensitizer and a photoinhibitor. Such a composition is used primarily for preparation of lithographic printing plates. Dueber does also disclose the preparation of colored images from color separation 2 I L negatives suitable for color-proofing. The Dueber invention is directed to photopolymerizable composition which are developed by conventional means and not by an electrostatic process.

Although various photopolymerizable compositions are disclosed by other inventors to be useful in electrophotography, photopolymer electrostatic masters capable of duplicating the image characteristics of a printing press are only now being developed. It is desirable to provide positive or negative images from a single photopolymer electrostatic master since such a master will satisfy the proofing needs of all printers whether they use negative or positive color separations.

It has now been found that negative or positive images can be provided which are substantially duplicates of a printing press by exposure means described more fully below utilizing a photohardenable electrostatic master having a layer containing a polymer binder, ethylenically unsaturated compound, o photoinitiator, photoinhibitor and at least one visible light sensitizer.

BRIEF DESCRIPTION OF THE DRAWING I Fig. 1 illustrates a schematic flow chart of the basic process steps for forming a negative image and a positive image from a photohardenable electrostatic master.

SUMMARY OF THE INVENTION In accordance with this invention there is a process '2 for producing a negative image from a photohardenable electrostatic master comprising 4 t imagewise exposing to visible radiation a photohardenable electrostatic master comprising an electrically conductive 30 substrate bearing a photohardenable layer comprising a polymeric binder, a compound having at least one ethylenically unsaturated group,

Q

1 3 S. 1 I a photoinitiator, a nitro aromatic photoinhibitor, and at least one visible light sensitizer; exposing at least the unexposed image areas to ultra violet radiation charging electrostatically the photohardenable electrostatic master to form a latent image of electrostatic charge on the imagewise exposed areas; developing the charged latent image by applying an electrostatic toner of opposite charge; and transferring the toned image to a receptor surface.

In accordance with this invention there is also provided a process for producing a positive image from a ooo photohardenable electrostatic master comprising imagewise exposing to ultraviolet radiation o9 a photohardenable electrostatic master o2 comprising an electrically conductive o substrate bearing a photohardenable layer comprising a polymeric binder, a compound having at least one '235 ethylenically unsaturated group, a photoinitiator, a nitroaromatic photoinhibitor, and at least one visible light sensitizer; 4

C

d. 4

A.

A yt)

S

S5 exposing overall the photohardenable electrostatic master to visible radiation; charging electrostatically the photohardenable electrostatic master to form a latent image of electrostatic charge on the imagewise exposed areas; developing the charged latent image by applying an electrostatic toner of 0 opposite charge; and transferring the toned image to a receptor surface.

DETAILED DESCRIPTION OF THE INVENTION 15 The formation of the negative or positive .images and color proofs is made possible by use of a photohardenable (photopolymerizable) electrostatic master which bears on the electrically conductive support a photohardenable layer comprising an organic S20 polymeric binder, a compound having at least one *4o ethylenically unsaturated group which can be a monomer, a photoinitiator. a photoinhibitor, and at least one visible light sensitizer. Preferably a i chain transfer agent is also present. Other ingredients can also be present as set out below.

S' Polymeric binders, ethylenically unsaturated compounds, photoinitiators, including preferred hexaarylbiimidazole compounds (HABI's) and chain transfer agents are disclosed in Chambers U.S. Patent 3,479.185, Baum et al. U.S. Patent 3,652,275, Cescon U.S. Patent 3,784,557, and Dueber U.S. Patent 4,162,162, the disclosures of each of which are incorporated herein by reference.

This invention is based on the discovery 6 which comprise, for example, a nitroaromatic compound photoinhibitor and at least one arylylidene aryl ketone sensitizer compound, are capable of producing both positive and negative images depending on the exposure sequence and exposure wavelengths used. The nitroaromatic compound photoinhibitors in which the nitro group is ortho to a hydrogen-bearing alpha-carbon substituent do not significantly retard or inhibit free-radical polymerization in certain photopolymerizable systems, but are photochemically rearranged to nitrosoaromatic inhibitors of free-radical polymerization by exposure to radiation having a wavelength of about 200 to about 400 nm.

fetl i These nitroaromatic compounds are relatively unaffected by radiation of longer wavelength. On the "other hand, certain radiation-sensitive, free-radical S, initiators absorb radiation of longer wavelength, especially in the presence of added sensitizers, to provide sufficient radicals for polymerization of a polymerizable monomer in the absence of an I o" appreciable concentration of inhibiting nitrosoaromatic species.

SThe nitroso compounds formed by irradiation of the nitroaromatic compounds described herein with short wavelength radiation interfere with the normal free-radical induced polymerization process. Thus, when using the shorter wavelength region of the spectrum in the presence of a nitrosoaromatic compound, on subsequent exposure with visible light, which causes cleavage of the biimidazole, an insufficient number of initiating and propagating free radicals are available, and polymerization does not occur. When a composition of this invention is exposed to radiation of wavelength greater than about 400 nm. the nitroaromatic compound is relatively 6 unaffected, and the photoiniatiator system operates to produce initiating radicals. These radicals are able to effect chain propagation in the usual way and polymerization occurs.

In the method of making negative images the imagewise visible radiation exposure wavelength ranges from greater than about 400 to about 800 nm, preferably about 400 to 600 nm. In the method of making positive images at least about 80% of the I0 radiation in the imagewise exposure has a wavelength of 200 to about 400 nm, preferably 300 to 380 nm.

The overall exposure in preparing positive images is visible radiation having a wavelength ranging from og greater than about 400 to about 800 nm, preferably 15 S15about 400 to 600 nm.

akin pBinders Suitable binders include: the polymerized methylmethacrylate resins including copolymers thereof, polyvinyl acetals such as polyvinyl butyral S 20 and polyvinyl formal, vinylidene chloride copolymers vinylidene chloride/acrylonitrile, vinylidene chloride/methacrylate and vinylidene chloride/vinylacetate copolymers), synthetic rubbers butadiene/acrylonitrile copolymers and chloro-2butadiene-1,3-polymers), cellulose esters cellulose acetate, cellulose acetate succinate and cellulose acetate butyrate), polyvinyl esters polyvinyl acetate/acrylate. polyvinyl acetate/methacrylate and polyvinyl acetate), polyvinyl chloride and copolymers polyvinyl chloride/acetate), polyurethanes. polystyrene.

Preferred binders are poly(styrene/methylmethacrylate) and polymethylmethacrylate.

The resistivity of the binder largely contributes to the total resistivity of the 7 I I 8 photohardenable composition in both exposed and unexposed areas. However, it is the resistivity of the photopolymer matrix or total composition that controls image characteristics and dot gain. If the total resistivity of the unexposed composition is too small, the charge will decay too rapidly in the unexposed areas losing the highlight dots. On the other hand, if the resistivity of the photopolymer composition is too high the discharge rate may be too 1 slow, resulting in overtoning solids and plugging of shadow dots. The preferred resistivity of the exposed photopolymer composition, for the present n* 14 16 application, is about 10 to 10 Q-cm, corresponding to a binder resistivity in the 1016 120 S* to 10 n-cm range. For different applications a 'ft different resistivity for the binder may be desired.

Ethylenically Unsaturated Compounds Any ethylenically unsaturated photopolymerizable or photocrosslinkable compound identified in the prior patents for use in HABI-initiated systems can be used. The term "monomer" as used herein includes simple monomers as well as polymers, usually of molecular weight below 1500, having crosslinkable ethylenic groups. Preferred monomers are di-, triand tetra-acrylates and -methacrylates such as Sethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, glycerol diacrylate, glycerol triacrylate, ethylene glycol dimethacrylate, 1,2-propanediol dimethacrylate, 1,2,4butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, 1,4-benzenediol dimethacrylate.

pentaerythritol tetramethacrylate, 1,3-propanediol diacrylate. 1,5-pentanediol dimethacrylate, pentaerythritol triacrylate; the bisacrylates and 3methacrylates of polyethylene glycols of molecular 8 t weight 100-500, etc. A particularly preferred monomer is ethoxylated trimethylolpropane triacrylate.

Initiators Preferred initiators are the HABI photoinitiators. 2,2'4,4',5,5'-hexaarylbiimidazoles, sometimes called 2,4,5-triarylimidazolyl dimers, which dissociate on exposure to actinic radiation to 1 form the corresponding triarylimidazolyl free radicals. As indicated above, HABI's and use of HABI-initiated photopolymerizable systems for Sapplications other than for electrostatic uses are disclosed in a number of patents. These include: Cescon U.S. 3,784,557; Chambers 3,479,185; Chang et Sal. U.S. 3,549,367; Baum et al. U.S. 3,652,275; oa,- Dueber U.S. 4,162,162; Chambers et al. U.S.

4,264,708; and Tanaka et al.. U.S. 4,459,349; the disclosures of these patents are incorporated herein by reference. Any 2-o-substituted HABI or mixtures thereof disclosed in the prior patents can be used in o "o °a this invention unless they absorb strongly in the range of 300 to 400 nm. The HABI's can be represented by the general formula 3 N 3 N N s 4\ /s 4' R R R R where the R's represent aryl radicals. The substituted HABI's are those in which the aryl radicals at positions 2 and 2' are ortho-substituted.

The other positions on the aryl radicals can be 9 unsubstituted or carry any substituent which does not interfere with the dissociation of the HABI upon exposure or adversely affect the electrical or other characteristics of the photopolymer system.

Preferred HABI's are 2-o-chlorosubstituted hexaphenylbiimidazoles in which the other positions on the phenyl radicals are unsubstituted or substituted with chloro, methyl or methoxy. The most preferred HABI's are 2,2'-bis(o-chlorophenyl)- 4,4',5,5'-tetrakis(m-methoxyphenyl)-biimidazole and 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole.

0 0 1 Processes for producing HABI compounds result in a mixture of isomers and other impurities.

15 Use of high concentrations of these impure materials 0,O: can provide photopolymerizable compositions with high sensitivity but poor shelflife or storage stability due to crystallization. It has been found that purification of the materials by various methods can o 20 provide relatively pure materials which can be used Sin high concentration without crystallization.

o 00 The HABI's can be purified sufficiently for Suse in this invention by merely dissolving them in methylene chloride, filtering and recrystallizing by adding methanol or ether. If desired, the solution 00," of the HABI in methylene chloride can be eluted through a silica gel column prior to recrystallization.a preferred method for purification of o-Cl-HABI is as follows: o-Cl-HABI 225 g of o-Cl-HABI 205-7 0 C) is added to 1800 ml methylene chloride and the solution is heated to boiling. 150 g DARCOO G-60 charcoal activated, EM Science, a Division of EM Industries, Inc., Cherry Hill. NJ is then added. The mixture is 11 kept boiling for 30 to 45 min. prior to hot filtration through Celite® diatomaceous Silica Product. Manville Products Corp.. Denver, CO under vacuum. The filtrate is concentrated to yield ca.

135 g solid with m.r. 203-5 0 C. The-filter pad is washed with 200 ml of methylene chloride and the filtrate is concentrated to yield ca. 45 g solid with m.r. 203-207 0

C.

Photoinhibitors Useful photoinhibitors of nitroaromatic compounds are disclosed in Pazos U.S. Patent 4,198,242, the disclosure of which is incorporated Sherein by reference. Useful compounds of this type are of the formula:

R

1 R2 NO 2 I t 2 N 0 2 5 6 3

CHR

5

R

R

wherein

R

1

R

2

R

3 and R 4 alike or different are H, OH. halogen, NO 2 CN. alkyl of 1 to 18 carbons.

alkoxy in which the alkyl is of 1 to 18 carbons, acyloxy of 2 to 7 carbons, aryl of 6 to 18 carbons, benzyl, halogen-substituted phenyl, polyether of 2 to 18 carbons and 2 to oxygens, dialkylamino in which each alkyl is of 1 to 18 carbons, thioalkyl in which the alkyl is of 1 to 18 carbons, or thioaryl in which the 2 3 aryl is of 6 to 18 carbons, R and R 3 taken together are -OCH 2 0 or CH20-+- in which q is an integer from 1 to 5, or any two of R 11 1 12 2 3 4 R R and R taken together are the residue of a second benzene ring fused into the benzene nucleus, with the proviso that not more than one of 1 2 3 4 R R R and R is OH or NO 5 R is H, alkyl of 1 to 18 carbons, halogen, phenyl, or alkoxy in which the alkyl is of 1 to 18 carbons, R6 is H, OH, alkyl of 1 to 18 carbons, phenyl.

alkoxy in which the alkyl is of 1 to 18 carbons.

10 or aryloxy of 6 to 18 carbons unsubstituted or substituted with halogen, alkyl of 1 to 6 carbons, or alkoxy of 1 to 6 carbons, with the St 5 6 t proviso that only one of R and R is H. or 5 6 R and R together are =CH2, -O-CH 2 =NC6H 5 15 t 1 5 =NC6H N(alkyl) 2 in which each alkyl is of 1 to 18 carbons, -O-C2H =N(alkyl) in which the alkyl is of 1 to 6 carbons,

R

1 ON -R 2 =N(hydrocarbylene) N=CH R

R

4 I I in which the hydrocarbylene group is of 1 to 18 carbons, or C==NH-C= C R7 R8 R 9 R8 R R in which R 8 and R alike or different, are H or 7 10 alkyl of 1 to 4 carbons, and R and R alie or different, are -CN -COR 11 in which R 11 is alkyl 12 L I A 13 of 1 to 5 carbons, or -COOR 12 in which R 12 is alkyl of 1 to 6 carbons which may be interrupted by an oxygen atom, alkenyl of 2 to 5 carbons, or 7 8 alkynyl of 2 to 5 carbons, or R and R together, 9 10 or R and R together, complete a 6-membered carbocyclic ring containing a keto group.

In the formula for nitroaromatic compound described above the preferred alkyl groups are lower alkyl groups containing 1 to 6 carbon atoms. In the Sbis compounds, the term "hydrocarbylene" represents any divalent radical composed solely of carbon and hydrogen containing 1 to 18 carbon atoms. Typical radicals include and p-phenylene, vinylene, 2-butylene, 1,3-butadienylene, hexamethylene, octamethylene, octadecamethylene, naphthylene (1,2; 2,3; 1.4; and

CH

2 CH 4 ea 0 4 4 and the like.

It has been found that the nature of the R and R substituents in the nitroaromatic compounds is very important. The unsubstituted 30 5 6 compounds in which R and R are H do not seem to work satisfactorily. Furthermore, some R and R substituents deactivate the CH moiety toward rearrangement, for example, substituents which are normally considered to destabilize positive charges.

such as nitro, cyano, carboxy and 2-pyridyl. It has been found, for instance, that 13 14 NO NO 2 2 2 Sand

N

H

2 Co2H CH 2 do not work in accordance with this invention.

Preferred nitroaromatic compounds include those wherein

R

1 is H or methoxy; 2 3 R and R are H, alkoxy of 1 to 6 carbons.

polyether of 2 to 18 carbons and 3 to 10 oxygens, t f t tit$ alkyl of 1 to 6 carbons, or acetoxy; or t 15 R 2 and R 3 taken together, are -OCH 0- or 2 t I CH (et 4 2 2 5 t i, R is H; 5 t R is H, alkyl of 1 to 6 carbons, alkoxy of 1 to 6 carbons; or phenyl R6 is OH. alkoxy of 1 to 6 carbons, or phenoxy t substituted with up to three chlorines, alkyls of S1 to 6 carbons, or alkoxys of 1 to 6 carbons; or 5 6 R and R 6 taken togetner, are =NC 6H 25 t

R

1 .2

R

0 =N(hydrocarbylene) N=CH R

R

4 14

I

in which the hydrocarbylene group is of 2 to 6 carbons, =N (alkyl) in which alkyl is n-alkyl of 1 to 6 carbons or t-butyl. or C =C NH- C C 1 R7 R8 R9 in which R and R 9are alike and are H or methyl, and R7and R 0are alike and are -CN. -COR 1 1 in which R H is methyl or ethyl, or -COOR 12in which R 12 is methyl or ethyl.

Particularly preferred, because the instant layers exhibit high imaging speeds, are nitroaromatic Afro~ compounds wherein 1and RH are H; a2 3 88R and R are alike and are alkoxy of 1 to 6 carbons; *8~1 R is H. or alkyl of 1 to 6 carbons; a 6 is alkoxy of 1 to 6 carbons, or phenoxy substituted With up to two alkoxys of 1 to 6 carbons; or R 20 6 ~and R taken together, are =0 or =NC 6H 1 4 4 8 Specific nitroaromatic compounds which are suitable include: a8o-nitrobenzylalol o-nitrobenzaldehyde a-phenyl-o-nitrobenzyl alcohol o- (diphenylmethyl )nitrobenzene a-phenyl imino-o-nitrotoluene a. a-diethoxy-o-nitrotoluene aLa-ethylenedioxy-o-nitrotoluene 3-methoxy-2-nitrobenzaldehyde 4-methoxy-2--nitrobenzaldehyde 3, 4-dimethoxy-2-nitrobenzaldehyde 3.4-dimethoxy--2-nitrobenzyl alcohol 4-cyano-2-nitrobenzaldehyde j t r 1 1 I I

I'

I I I III

II

5-hydroxy-2-nitrobenzaldehyde 4-hydroxy- 3-methoxy-2--nitrobenzaldehyde 1-nit ro- 2-naphthaldehyde 2.3.4,5-tetramethyl-6--nitrobenzyl alcohol 53,4.5-trichloro-2-nitrobenzaldehyde 3, S-dibrono--4,6-dichloro--2-nitrobenzaldehyde 4.5-dimethoxy-2-nitrobeizyl alcohol 4. 5-dimethoxy-2--nitrobenzaldehyde 2. 4-dinitrobenzaldehyde 5-tolyl--2-nitrobenzaldehyde 5-benzyl-2-nitrobenzaldehyde (m-chlorophenyl )-2-nitrobenzaldehyde 4- (2-methoxyethoxy)-2--nitrobenzaldehyde 4-ethoxyethyl--2-nitrobenzaldehyde 3-diethylamino-2-nitrobenzaldehyde 4-butylthio-2-riitrobenzaldehyde 4-phenylthio-2-nitrobenzaldehyde 2-nitrostyrene 4. 5-diiethoxy-2-nitrostyrene a-(p-diinethylaminophenyl)imino-2-nitrotoluene 4. 5-dimethoxy-2-nitro-a-phenyliminotoluene 2-nitrostyrene oxide 2-nitrocumene 4.5-dimethoxy-2-nitrobenzyl chloride 25 axa-ethylenedioxy-2-nitrotoluene NN'-bis(4,5-dimethoxy-2-nitrophenylmethylene)- 1.*6-hexanediamine N.N' -bis 5-dimethoxy--2-nitrophenylmethylene)- N.N' -bis 5-dimethoxy-2-nitrophenylmethylene) -mphenylenediamine NUN' -bis(4.5-dimethoxy-2-nitrophenylmethylene)-pphenylenediamine N.N'-bis(4.5-dimethoxy-2-nitrophenylmethylene)a.cz'-bi-p-toluidine I II I I II I It I I I II C C 17 NN' -bis(4..5-dimethoxy-2-nitrophenylniethylene)- 4,4' -stilbenediamine dimethyl ester of 2,6-dimethyl-4--(2'-nitrophenyl)- 1,4-dihydropyridine-3 .5-dicarboxylic acid diethyl ester of 2,6-dimethyl-4-(2'-nitrophenyl)- 1.4-dihydropyridine-3 ,5-dicarboxylic acid diethyl ester of 2,6-dirnethyl-4-C2'-nitro-4'.5'-di- Iethoxy-phenyl)-1,4.-dihydropyridine-3 dicarboxylic acid di-n-propyl ester of 2.6-dirnethyl-4-(2'-nitrophenyl)- 1.4-dihydropyridine-3,.5-dicarboxylic acid diisopropyl ester of 2.6-dimethyl-4-(2'-nitrophenyl)- 1,4-dihydropyridine-3.5-dicarboxylic acid di(B-ethoxyethyl)ester of 2.6-dimethyl-4-(2'-nitro- 15phenyl)-l,4--dihydropyridine-3 .5-dicarboxylic acid diallyl ester of 2.6-diinethyl--4-(2--nitrophenyl)t II 1.4-dihydropyridine-3.5-dicarboxylic acid Ctt dipropargyl ester of 2.6-diniethyl-4-(2'-nitrophenyl)- 1.4-dihydropyridine-3,5-dicarboxylic acid 3-rnethyl-5-ethyl ester of 2.6-dimethyl-4-(2'-nitrophenyl 4-dihydropyridine-3. 5-dicarboxylic acid ester of 2,6-dimethyl-4-(2'nitrophenyl)-1.4-dihydropyridine-3.5-dicarboxylic acid 25 ethyl ester of 4-(2'-nitrophenyl)-2,6-dinethyl-3aceto-1.4-dihydropyridine-5-carboxylic acid 2.6-dimethyl-4-(2'-nitrophenyl)-3.5-diaceto-1.4dihydropyridine 2.6-dimethyl-4-(2'-nitrophenyl)-3.5-dicyano-1.4dihydropyridine ethyl ester of 2-methyl-4-(21-nitrophenyl)- 8-hexahydro-5-oxoquinoline-3-carboxylic acid methyl ester of 2-methyl-4-C2'-nitrophenyl)- 351.4.*5.6.7. 8-hexahydro-5-oxoquinoline-3-carboxylic acid 18 isopropyl ester of 2-methyl-4-(2'-nitrophenyl)- 1.4. 5.6.7. 8-hexahydro-5-oxoquinoline-3--carboxylic acid *4 8,*9.10-decahydro-9-(2 '-nitrophenyl)-1, 8dioxoacridine *8 10-decahydro-3 .3.*6,6-tetramethyl-9- (2i-nitrophenyl)--1.8-dioxoacridine pherioxy) ethane 101-(2'-nitro-4'.5'-dilethoxy)phenyl-l-phenoxyethane 1-(2'-nitro-4'.5-dinethoxy)phenyl--(2.4.dimethyl.

phenoxy )ethane 1-(2'-nitro-4'.S--dimethoxy)phenyl--(4-choro.

phenoxy )ethane 151-(2'-nitro-4'.5'-dilnethoxy)phenyl-1-(4-bromophenoxy)ethane 1-(21-nitro-4'.5'-dimethoxy)phenyl-l-(2-naphthyloxy) ethane 1-(2'-nitro-4.5-dimethoxy)phenyl--(24-dimethoxy.

vt 2 phenoxy)ethane II 1-(2'-nitro-4'.5'-dimethoxy)pheriyl-l-(4-t-butylphenoxy) ethane 1-(2'r-itr-4'.5'-dimecLthoxyheyl.-1-(2-t-butyl *s 252-nitro-4.5-dimethoxy-a-mebtyliminotoluene 2-nitro--4.5-dimethoxy-cz-n-hexyliminotoluene. and ~1 1-(2V-ni.tro-4 .51-dimethoxy)phenyl--(2.4.5trimethylphenoxy)ethane.

The nitroaromatic compounds are ordinarily employed in concentrations of about 0.5 to about 15.0% by weight based on total weight of the polymerizable composition. The preferred amount in 18 19 any specific case will depend upon the particular monomer/free-radical generating system employed. In general, the preferred amount of nitroaromatic compound is about 1 to about 7% by weight based on total weight of polymerizable composition.

Visible Light Sensitizer Useful visible light sensitizers include the arylylidene aryl ketone visible sensitizers which are disclosed in Dueber U.S. Patent 4.162.162. the disclosure of which is incorporated herein by reference. Useful compounds of this type are of the formulae: O R6 A.

R

1 II o~ o CH-+CH CH N R 0 N( o- R R R 1 20 3 4 oo*o wherein 0 O 25 A. B, D. E are carbon atoms or one may be solely Sa nitrogen atom; 3 3

R

1 is H. OH or

R

2 is H. OH. CH30 or N(R7)2:

R

3 is H. OH or a is 0 or 1: Z is >CHOH. >C(CH3). -(-CH2--b wherein b is 1. 2 or 3.

0 C- O CH S CH 19 j I wherein R' is H. phenyl. or Z is linked with R 4 where Z is and R is or >N-CH 3 a being 0;

R

4 is H, CH OH. CH 0;

R

5 is H or R 5+R 7 is -CH CH2-. -CH CH CH2-, -O-CH 2CH

R

6 is H or R6+R 7 is -CH2CH-- -CH2CH-2CH-.

6 6 7 22' 22 2 0-CH CH and R7 is CH 3 -(CH 2

-CH

3 where n is 1 to -CH2 CH 2-Cl. -CH CH 2OH. CH CH OCH 3; 0 4 44 0 tttw 0044 o o n op 0 6 a4 0 00 4 0 4 1 *44t 4 0 t* 4 0 R 2 R 0

R

B A R 6 R R -4 R 7 wherein A. B. D are carbon atoms or one may nitrogen atom; R is H. CH 3

-OCHCH

2 OR. wherein R -CH CH OR' wherein R' is CH 3 or R is H. CH OH. or CH 0; R is H. OH. CH 30. CH F. Br. CN or R 2+R 3 is -O-CH

R

4 is H. CH 3 or R5 is H, CH 3

-OCH

2

CH

2 OR. wherein R -CH CH OR' wherein R' is CH 3 or

R

6 is H, CH 3 or phenyl; 6 3 R is H. CH 3 OH or CH 0;

R

8 is H; 8 R0

N

R

8 be solely a is H. CH 3 CH3CH 2-; N(R10)2: is H. CH 3 CH CH

JA~A

I

t 21 R +R1o is -CH2CH2-. -CH2CH2CH2- -OCH2CH2; R is H, R9+R10 is -CH2CH2-, -CH2CH2CH2 -OCH2CH and is CH 3 -4--CH2 CH 3 wherein n is 1 to and O R

I

C

S= CH -NR2-2or 0 R 1 15 CH -N(R 2 0 o t t 0 wherein G is C or

R

1 is H. CH or -OCH 3 and R is CH or -CH CH 3 the ketone having its maximum absorption in the range of 350 to 550 nm.

25 Preferred sensitizer compounds which are present in sensitizing amounts, generally 0.05 to by weight, preferably 0.2 to 4% by weight based on the total weight of photopolymerizable composition.

are of the following structures: 06

SR

7 R2 R 7 *2

I

R 1is H. OH. CH 3 0-: R 2is H. OH. CH 3 O0-: R 3is H. OH. CH 30-. with the proviso that if one of R 1 R 2 or R 3 is OH then the remainder must be H or CH 3 0-: Z is

CHOH,

\/CH 3 CH3 o 4* 4 4 *444 *0* 43*.

*4 o 4 .4, 4 4 4 t 4 .44.

$4 3 4 4 4 II 44 4 4 *4 04 04 4 *4 4*4.3 444443

I

4* 43 41 4 4

(CHR

2 awherein a wherein RI is H.

Z is linked is 1. 2 or 3.

-0 phenyl, or with R 4where Z is 41 C H and R 4is or 3 R4is H. CH 3 OH. CH 3 O0- with the proviso that if one of R 1 j R 2 or R 3is OH then R is one of H. CH or CH 0-; 3 3 R is Hor R 5-R 7is -CH 2CH2-' CH2CH 2CH-s -0-CH CH 2- R is HorR 6+R 7is -CH 2CH2-' -CH CH 2CH2-P -0--CR CH 2- R 7is CH 3 CH 3CH 2 -;i 23 o

R

6 6E R R 7 8 R14 5 R1 is H. CH3 R2 is H. OH, CH3 CH 0; R is H. CH OH, CH O; R 2 +R 3 is -O-CH

R

4 is H. CH CHO-; R is H, CH 4 5 3' R6 is H. CH 3 R is H. CH 3 OH. CH 0 with the proviso that if 7 3 3 one of R 2

R

3 or R 7 is OH then the remainder must H. CH or CH 0-; 3 3 R is H. R +R is -CH CH -CH CH CH 0 0 a 8 8 10 2 2 2 2 2 -O-CH CH 2 2 R H is H. R +R is -CH CH -CH CH CH a*09 9 10 2 2- 2 2 2 -O-CH CH 2 2 R is CH 3 CH CH- 10 3& 3 2 4 Some useful sensitizers include: 4 2-(4'-diethylamino-2'-methylbenzylidene)-l-indanone 2-(4'-diethylaminobelzylidene)-3-hydroxy--idalone 8-(4'-dimethylaminobenzylidefe)-acenaphthalene-7-one 2-(4 -diethylamino-2'-methylbenzylidene)-l-tetralone 4-diethylamino-2-methylbenzylideneacetophenofe 4 -dimethylaminobenzylidele-4dimethylamifoacetophenone 1-diethylamino-21-methylbenzylidene-2-(B ethoxy)-ethoxy)acetophenone 24 4' -diethylamino-2 '-methylbenzylidene-2-methylaceto.

phenone 4 '-diethylamino-2 '-methylbenzylidene-4-fluoroacetophenone 4 '-diethylamino-2 '-methylbenzylidene-4.cyanoaceto.

phenone 2-(4 '-diethylaminobenzylidene)-3-phenyl-lchromanoie 2- (4'-diethylaminobenzylidene)-l-chromanone 2- (4'-diethylamrinobenzylidene)-chroman-.3-dione 2 4 1 -di(B-chloroethyl)aminobenzylidene)3hydroxy- 1- inda none 2 4 '-diethylamino-2'1Iethybenzyidene)3-hydroxy- 1-i nda none boo. 2 41 -dimethylaminocinnamylidene)-3-hydroxyl- Delp indanone 2- (4 -diethylamino-2 '-methylbenzylidene)-l-tetralone 0 t9o 9:0.2- (4'-diethylarnino-2 '-methylbenzylidene)-l-benzo- :suberone 9 2 4 1-diethyamino2..methybenzyidene)...6 dimethoxy- 1-inda none 4 '-diethylamino-2 '-methylbenzylidene-3,4methylenedioxyacetophenone 4'-diethylamnino-2 S-methylbenzylidene-4methoxyacetophenone 4 -diethylamino-2 '-methylbenzylidene-3- 0 methoxyacetophenone 4 '-diethylamino-2 '-rethylbenzylidene-4met hylace tophenone 2- (4'-diethylamino-2 '-methoxybenzyl idene indanone 2- (9'-julolyidene)-l-indanone 2 4 '-diethylaminobenzylidene)...tetralone 2-(4 -diethylaminobenzylidene)-.propiophenone 2-(4 '-diethylamino-2 '-methylbenzylidene)..propiophenone 4-diethylaminobenzylidene-deoxybenzoin 2-(4 '-diethylaminobenzylidene)-1-indanone 24 2-(4'-diethylamiinobenzylidene)-3-gemdimethiyl-l-indanone 4'-diethylamino--2'-methylbenzylidene-4-hydroxyacetophenone 4 '-dimethylaminobenzylidene-3-hydroxyacetophenone 2-(N-ethyl-l, 2, 3,4-tetrahydro-6-quinolylidene-lchromanone.

The arylylidene aryl ketones can be prepared according to procedures set forth in Examples 1 and 32 of Assignee's U.S. Patent 4,162.162 by reacting specific aryl ketones and p-dialkylaminoarylaldehydes.

After purification, melting points, ultraviolet spectral data can be determined as described in the above identified patent. The sensitizers absorb radiation in the broad spectral range of 300 to 700 nm. The maximum absorption (A )is in the range of 350 to 550 n preferably 400 to 500 nm.

The photohardenable composition preferably ocontains a chain transfer agent.

Any chain transfer agent (CTA) identified in the prior patents for use with HABl-initiated photopolymerizable systems can be used. For example, O 00,Baum et al. U.S. Patent 3,652,275 lists N-phenylglycine, l.1-dimethyl-3,5--diketocyclohexane, and organic thiols such as 2-mercaptobenzothiazole, a 2-mercaptobenzoxazole, 2-mercaptobenzimidazole.

pentaerythritol tetrakis (mercaptoacetate), 4-acetamidothiophenol. mercaptosuccinic acid, dodecanethiol, and beta-mercaptoethanol. Others can be used include various tertiary amines known in the art, 2-mercaptoethane sulfonic acid, 6-mercaptopurine monohydrate, bis-(5-mercapto-l,3,4-thiodiazol-2-yl.

imidazole, and 2-mercapto-4sulfo-6-chlorobenzoxazole. The preferred CTA's are S1 1 26 2-mercaptobenzoxazole (2-MBO) and 2-mercaptobenzothiazole (2-MBT). 2-MBO and 2-MBT may be purified as illustrated below for 2-MBO: 2-MBO: Optimum Melting Point 193-194 0

C

For slightly impure lots 191-193 0 C) the following procedure is employed: A slurry of 300 g 2-MBO in 1500 ml methanol is stirred for 5 to 10 minutes and allowed to settle. Generally, the solvent layer assumes a red appearance due to impurities. The undissolved solid is filtered through #5 filter paper in a Buchner funnel with house vacuum. Solid is washed with cold methanol (1 100 ml portion), collected and dried in oven at 70-80°C for 3 to 5 hours, subset 15 quently pulverized and dried for an additional hour.

SYield is approximately 150 g of white powder, Sm.p. 193-194 0

C.

For impure lots below 191 0 C) the following procedure is used: 250 g brown 2-MBO, 50 g DARCO 1500 ml methylene chloride and 600 ml methanol are stirred in a 4 liter Erlenmeyer flask with gentle boiling for 30 to 40 minutes. The mixture is fil- S" tered hot through fast paper under low vacuum.

The red liquor that is collected is concentrated under low vacuum until 2-MBO precipitates out of solution. 200 ml of fresh methanol is added, and the resulting slurry is agitated to break up large lumps.

The slurry is filtered through slow paper and washed with 50 ml fresh methanol. The colorless precipitate is collected and dried at 70 to 80 degrees for 3 to 5 hours as above. Yield of product, melting above 192 0 C is ca. 26 27 Additives In addition to the primary ingredients and chain transfer agent, the photohardenable compositions can contain conventional ingredients such as co-initiators, thermal stabilizers, plasticizers, brighteners. UV absorbers, electron acceptors, electron donors, etc. The preferred thermal stabilizer is 1,4,4-trimethyl-2,3diazobicyclo-(3.2.2)-non-2-ene-N,N-dioxide (TAOBN).

Leuco dyes can also be present, Leuco Malachite Green, Leuco Crystal Violet, and leuco dyes disclosed by Baum etal U.S. Patent 3.652,275, column 7, line to column 11, line 31, the disclosure of which is incorporated herein by reference, etc. and produce a oa*o 15 printout image. Some leuco dyes, however, are not 4,.

stable in a strongly acid environment.

Useful electron donors have an oxidation potential, Ed of less than 2.5 eV and electron acceptors have a reduction potential, Ea of larger than -3.0 eV. Specific electron donor compounds which must be different type compounds from the initiators described above include: aromatic amines, triphenyl amine, diphenyl amine, methyl diphenyl amine, NN-dimethyl aniline, NN-diethyl 25 aniline, diethyl amine, triethyl amine, 1.4-diazabicyclo-[2.2.2]octane, N,N.N.N'-tetramethylbenzidine; arsenic, antimony, bismuth, phosphorous, and cyanide compounds, triphenyl arsine, triphenyl antimony, triphenyl bismuth, triphenyl phosphine, dimethylcyanamide, etc.; carbazole compounds, 9-ethyl carbazole, polyvinylcarbazole; olefins and cyclic aromatic compounds, naphthalene, cyanonaphthalene, 1,4-di-cyanonaphthalene, 1.1-diphenylethylene, indene, norbornadiene, quadricyclene; methoxy 27 1 28 compounds, 2-methoxynaphthalene.

1.3,5-trimethoxybenzene. o-dimethoxybenzene.

3-methoxypyrene, 3,4-dimethoxy-NN-dimethylaniline.

2,4-dimethoxy-N,N-dimethylaniline, 1,2-dimethoxy benzene; nitro compounds, nitrobenzene, p-dinitrobenzene; quinones, benzoquinone, electron acceptors, trinitrofluoreneone, p-biphenyl, pyridine, benzonitrile, di-cyanobenzene, pyrene-3-carboxylic acid, benzacridine, anthracene, benzanthracene, pyrene-4-carboxylic acid, 4-azaphenanthrene, benzophenone, acetophenone, 2,6,9,10-tertacyanoanthracene, 4-methylbenzoate. etc.

Triphenylamine is the preferred electron donor; biphenyl is a preferred electron acceptor.

Compositional Range iIn general, the essential components should be used in the following approximate proportions: 4- O4 binder 40-80 percent, preferably 45-65 percent; monomer 15-40 percent; preferably 25-35; initiator V 0.5-20 percent, preferably 0.5-10 percent; .o photoinhibitor 0.5-15 percent, preferably 1-7 percent; visible light sensitizer 0.05-10 percent, preferably 0.2-4 percent and preferably chain 25 transfer agent 0-5 percent, preferably 0.005-2 percent. These are weight percentages based on total weight of the photopolymerizable system. The preferred proportions depend upon the particular compounds selected for each component. For example, a high conductivity monomer can be used in smaller amount than a low conductivity monomer, since the former will be more efficient in eliminating charge from unexposed areas. The maximum total amount of additives will ordinarily be about 15% based on the total weight of the photohardenable composition.

28 \XI-ITi \-1 rrrr;-. i- P 1 4r *0 S 0 0 29 The Coating The photohardenable layer is prepared by mixing the ingredients of the photopolymerizable system in a solvent such as methylene chloride, usually in a weight ratio of about 10:90 to 40:60, coating a substrate, and evaporating the solvent.

Coating thickness should be uniform and about 4 to 18 im, preferably 7 to 14 um dry. Dry coating 2 weight should be about 40 to 180 mg/dm 2 preferably 70 to 140 mg/dm 2 The Support The conductive support may be a metal plate.

such as aluminum, copper, zinc, silver or the like; a conductive polymeric film; a support such as paper, 15 glass, synthetic resin and the like which has been coated on one or both sides with a metal, conductive metal oxide, or metal halide by vapor deposition or sputtering chemical deposition; a support which has been coated with a conductive polymer; or a support which has been coated with a polymeric binder containing a metal, conductive metal oxide, metal halide, conductive polymer, carbon, or other conductive fillers.

25 Exposure A special advantage of the photohardenable electrostatic master is that it can be used to prepare both positive and negative images. Positive images are prepared by a two-exposure procedure whereas negative images are prepared by a one-exposure technique. The photohardenable layers are exposed to radiation of wavelength in the 200-800 nm range.

4 9 a« 49 ft 4 *9 r€ -j r 04499 4 9 4 449'' 4. 1 t 4 Suitable sources of such radiation, in addition to sunlight, include carbon arcs, 29 mercury-vapor arcs, fluorescent lamps with ultraviolet radiation-emitting phosphors, argon and xenon glow lamps, electronic flash units.

photographic-flood lamps, and lasers. Other fluorescent radiation sources such as the tracings on the face of a cathode ray tube may be used. Electron accelerators and electron beam sources through an appropriate mask may also be used.

Where artificial radiation sources are used, the distance between the photosensitive layer and the radiation source may be varied according to the radiation sensitivity of the composition and the nature of the photopolymerizable compound.

Customarily, mercury-vapor arcs are used at a 15 distance of 1.5 to 60 inches from the IP ^photopolymerizable layer. Radiation fluxes of *T 10-10,000 uw/cm are generally suitable for use.

During the first exposure in preparing a t positive image, impinging radiation having a wavelength of about 200 to about 400 nm is used, but is not necessary that the wavelength be limited to w*o this range. The radiation may have wavelengths over the entire range of about 200 to about 800 nm. In order to form an effective amount of inhibitor in the S 25 first exposure, at least about 80% of the radiation should be between about 200 and 400 nm; and preferably substantially limited to wavelengths of between 300 and 400 nm.

The radiation used during the second exposure should be substantially limited to wavelengths greater than about 400 nm. By "substantially limited" it is meant that the radiation is filtered to exclude greater than about of the radiation at about 400 nm and below, or is otherwise limited to radiation greater than about 400 I 31 nm. Preferably, the radiation in the second exposure has wavelengths substantially limited to greater than about 400 to about 800 nm. and most preferably about 400 to about 600 nm.

Although all of the photopolymerizable layers of this invention can be imaged with the second exposure radiation having wavelengths down to about 380 nm. shorter exposure times are generally experienced when wavelengths up to about 400 nm are filtered out since many of the nitroaromatic compounds absorb radiation that far out into the visible range. During the second exposure, a greater portion of the coating, typically the entire coated area, is struck by radiation with the result that free radicals are generated and polymerization takes place in the areas struck by radiation during the Ssecond exposure but not during the first exposure.

1, The length of time for which the compositions are exposed to radiation may vary upward from fractions of a second. The exposure times will vary, in part, according to the nature and concentration of the polymerizable compound and initiator, photoinhibitor, visible light sensitizer and the type of radiation. Exposure can occur over a 25 wide range of temperatures, as for example, from about -80oC up to about 4150°C with selected compositions. Preferred exposure temperatures range from about -30° to about +35 0 C. There is an obvious economic advantage to operating the process at room temperature.

Imagewise exposure, for example in preparing electrostatic masters, is conveniently carried out by exposing a layer of the photoactive composition to radiation through a process transparency: that is, an image-bearing transparency consisting solely of areas 31 i i i i S "1 1 I 32 substantially opaque and substantially transparent to the radiation being used where the opaque areas are substantially of the same optical density: for example, a so-called line or halftone negative or positive. Process transparencies may be constructed of any suitable materials including cellulose acetate film and polyethylene terephthalate film. An example is the preparation of a positive working electrostatic master using the novel system of this invention. In a positive imaging system, polymer is ultimately formed under the opaque areas of the process transparency; that is, the areas not struck by radiation passing through the transparency.

Exposure of a master coated with the nitroaromatic t, 1 0 15 compound-containing photoactive composition to the Sfull spectrum of a mercury-vapor lamp through a filter which allows radiation between 300-400 nm to reach the master and the cellulose acetate or polyethylene terephthalate film negative causes rearrangement of the nitroaromatic compound to a nitrosoaromatic compound in the radiation-struck areas. The areas struck by radiation during the j first exposure will become non-image areas since no polymerization will be initiated in these areas.

Removal of the process transparency followed by a second exposure of the master to radiation It tc substantially limited to wavelengths greater than about 400 nm causes polymerization to occur in the Sareas which were not struck by radiation during the first exposure. Radiation of this wavelength is insufficiently absorbed by the nitroaromatic compound to rearrange it to a nitroso compound. The portions of the coating exposed in this manner become the polymeric image areas. The doubly exposed element provides a positive working master suitable for use in color proofing applications, etc.

32 33 Negative mode images are formed when the photohardenable electrostatic master is initially exposed to visible light, light of wavelengths greater than 400 nm. They may be used immediately after removal of the cover sheet, or they may be exposed to ultraviolet light, prior to charging and toning. The effect of the visible light exposure is to effect photopolymerization, to harden the coating to make it less photoconductive, and the purpose of the second, ultraviolet light exposure, with light of 200 to 400 nm is to form inhibitor, to prevent room light from effecting polymerization in the previously unexposed areas. If the film is used Sin a red-light environment, however, this latter 15 ultraviolet light exposure is not required, since no polymerization will ensue in the absence of light.

The preferred charging means is corona discharge. Other charging methods, discharge of a capacitor, can also be used. Dry electrostatic toners are useful in the process. Any liquid Selectrostatic toner and any method of toner o application can also be used. Preferred liquid S electrostatic developers are suspensions of pigmented resin toner particles in nonpolar liquids which are charged with ionic or zwitterionic compounds. The nonpolar liquids normally used are the Isopar branched-chain aliphatic hydrocarbons (sold by Exxon t Corporation) which have a Kauri-butanol value of less than 30 and optionally containing various adjuvants are described in Mitchell U.S. Patent 4.631,244 and 4,663,264, Taggi U.S. Patent 4,670,370 and assignee's S09,oo9L 13 1 3S..15; l! 0 2 r following U.S. Patentsr 4, -v Fora o wi c h v Pe ?w v l o Re l s 33 j 1 34 .1 rn. 1 r. These are narrow high-purity cuts of isoparaffinic hydrocarbon fractions with the following boiling ranges Isopar®-G, 157-176 0

C.

Isopar® H 176-191°C, Isopar®-K 177-197 0

C.

Isopar®-L 188-206 0 C. Isopar®-M 207-254 0

C,

lsopar®-V 254-329 0 C. Preferred resins having an average particle size of less than 10 vm are copolymers of ethylene (80 to 99.9%) acrylic or methacrylic acid (20 to alkyl of acrylic or methacrylic acid where alkyl is 1 to 5 carbon atoms (0 to copolymers of ethylene and methacrylic acid having a melt index at 190 0

C

of 100. Preferred nonpolar liquid soluble ionic or zwitterionic components are lecithin and Basic Barium 15 Petronate@ oil-soluble petroleum sulfonate r manufactured by Sonneborn Division, Witco Chemical Corp., New York. NY. Many of the monomers useful in the photohardenable composition are soluble in these Isopar® hydrocarbons, especially in Isopar®-L.

Consequently, repeated toning with Isopar® based toners to make multiple copies can deteriorate the n electrical properties of the master by extraction of monomer from unexposed areas. The preferred monomers are relatively insoluble in Isopar® hydrocarbons, 25 and extended contact with these liquids does not unduly deteriorate films made with these monomers.

Photohardenable electrostatic masters made with other, more soluble monomers can still be used to make multiple copies, using liquid toner having a dispersant with less solvent action.

After developing, the toner image is transferred to another surface, such as paper for the preparation of a proof. Other receptors or surfaces include polymeric film, cloth, etc. For making integrated circuit boards, the transfer surface can

~II

I I 1 be an insulating board on which conductive circuit lines can be printed by this process, or it can be an insulating board covered with a conductor a fiber glass board covered with a copper layer) on which a resist is printed by this process. Transfer is accomplished by electrostatic or other means.

by contact with an adhesive receptor surface.

Electrostatic transfer can be accomplished in any known manner, by placing the transfer surface in contact with the toned image, applying a squeegee to assure maximum contact, and applying corona discharge to the backside of the transfer element.

It is preferred to transfer the image across a gap, :0 6 um.

INDUSTRIAL APPLICABILITY The photohardenable electrostatic master is particularly useful in the graphic arts field.

4.1° particularly in the area of color proofing wherein the proofs prepared duplicate the images achieved by printing. The photohardenable electrostatic masters S.0 0 of the invention satisfy the proofing needs of all 04 printers whether they work with positive or negative color separations because one such master is capable o25 of producing both positive and negative images.

Other uses for the photohardenable master include making integrated circuit boards and printing plates.

O EXAMPLES The following examples illustrate but do not limit the invention wherein the percentages and parts M are by weight. In the examples, ingredient designations have the following meanings

I

72

PMMA

BINDERS

polymethylmethacrylate T=1.25. where -n is the inherent viscosity 0 C. where Tg is the glass transition temperature poly(styrene/mnethylmethacrylate) (70/30) P SMMA

TMPEOTA

MONOMERS

ethoxylated trimethylo.

propane triacrylate

INITIATORS

*4 0 0 0-449 0444 o 0 *444 04 O 000 0440 0444 04 0 4 0 0 0 00 O 04 0 0 0 0 04 to 4 4 04 p 00*44,0 0 4, 000400 00 4,0 0 0 0 o-CL-HABI

CDM-HABI

2 -MBO 2 -MBT 2,*2 '-bis Co-chiorophenyl tetraphenylbiimidazole 2,2'-bis~o-chlorophenyl)-4.4'.5,5'tetrakis (m-methoxyphenyl)-biimidazole CHAIN TRANSFER AGENTS 2-znercaptobenzoxazole 2-mnercaptobenzothiazol e

PHOTOINHIBITORS

4. 5-dimethoxy-2-nitrobenzaldehyde l-(2'-nitro-4'.5'--dimnethoxy)phenyl-l-(4t-butyl phenoxy)ethane dimethyl ester of 2.6-dirnethyl.-4-(2'nitrophenyl 4-dihydropyridine-3. dicarboxylic acid 36 6 -NVA a-METHYL BPE

DHP-M

37 SENS ITI ZERS DABC 2-(4'-diethylaminobenzyljdene)-lchromanone DBI 2(4'-diethylamino-21-methylbenzylidene.

1-indanone ETQC ethyl-1,2.3.4-tetrahydro-6quinolylidene)---chrornanone ADDITIVE S 4tTLA-454 tris-(o-methyl-p-diethylaminophenyl)y a 15 methane LCV Leuco Crystal Violet p-TSA p-toluene sulfonic acid In the following examples parts and percentages are by weight. The numerals in Example 1 are identical with those shown in Fig. 1.

EXAMPLE 1 t 4 A photopolymerizable element was prepared having a 0.004 inch (0.0102 cm) aluminized polyethylene terephthalate support and a 0.00075 inch (0.002 cm) polypropylene cover sheet (not shown in Fig. The photopolymerizable layer had the following composition: 37 -f 38 INGREDIENT

AMOUNT

0-CL HABI 30.4 CDM HABI 30.4 a-METHYL BPE 41.4 2-MBO 1.4 TLA-454 20.7 LCV 5.46 DABC 6.86 ETQC 6.86 TMPEOTA 413.0 PSMMA 843.5 The coating weight of the photopolymerizable 15 layer was 119 mg/dm The photopolymerizable ,s element was exposed, through a negative color separation for 30 seconds using PER-105 idaylight (visible light 6) fluorescent lamps having 2 an intensity of 3.4 mw/cm 2 at the surface of the S 20 photopolymerizable element. The lamp output was measured with an IL-1700 Research Radiometer with an XRD140A detector from International Light Inc., Newburyport. MA. The cover sheet was peeled off leaving an element that retained charge in the 25 polymerized areas. Charge decay data showing charge retention after exposure to visible light was obtained in the following manner. Strips of film measuring 1.5 inches (3.81 cm) wide by 6 inches (15.24 cm) long were prepared. The bottom 3 inches were covered to prevent polymerization and the top 3 inches (7.62 cm) were exposed as indicated above.

After exposure, the film was placed on a iovable metal plate (not shown in Fig. 1) and grounded (7) with copper tape. The film was then transported at the rate of 1 inch/second (2.54 cm/second) under a 38 L A 39 single wire positive corona powered by a Model 251 Coronaply II Power Supply and the retained voltage in the exposed photopolymer was measured with a Model 244 Isoprobe Electrostatic Voltmeter as a function of time after charging as shown in Table 1 below. The power supply and voltmeter were from Monroe Electronics. Lyndonville. NY.

Time after Charging (seconds) 0 15 10 120 TABLE 1 Voltage Retained After 30 Seconds Visible Exposure 1064 848 722 648 366 250 Unexposed Area 51 9 3 0 I It I~ Ii 1411 4 44 ct I 4 1. 4 *t 4 4 4e 20 A similarly prepared photopolymerizable element was given a 1 minute exposure to black-light blue fluorescent lamps of 1.1 mw/cm 2 intensity.

The cover sheet was peeled off leaving an element which did not retain charge in the area exposed to the UV radiation. Charge decay data showing the absence of retained charge in the UV struck areas was obtained as above and is shown in Table 2.

Time after Charging (seconds) 0 15 TABLE 2 Voltage Retained After 1 Minute UV Exposure 20 0 0 0 Unexposed Area 51 9 3 0 A third sample of the photopolymerizable element was exposed, through a positive color separation (10) for 1 minute with UV radiation After removal of the color separation, the element was given a second overall exposure of seconds to visible light After the cover sheet was peeled off, the sample was charged by positive corona as the previous two samples, and the charge decay data shown in Table 3 was measured.

TABLE 3 Voltage Retained Time After Voltage Retained After Single Charging After Dual Second Visible (seconds) Exposure Exposure 0 36 1064 2 848 0 722 Table 3 shows that the first UV exposure (11) deactivated the photopolymer and prevented the second second visible light exposure (12) from polymerizing the photopolymer element.

Positive and negative toned images were produced from the photopolymerizable element prepared t 25 as described earlier as follows. Four 1.5 by 6 inch (3.81 x 15.24 cm) strips of the photopolymerizable element were prepared as described earlier and a Stouffer Graphic Arts step tablet phototool was placed over each sample. One strip was exposed for 1 minute with UV radiation using the light source described earlier, a second strip was exposed for 1 minute with visible light as described earlier.

the third and fourth strips were exposed for 1 minute with UV radiation (11) followed by 1 minute and minute of visible light respectively. After 41 exposure, the cover sheets were peeled off, and the four gamples were wet with Isopar®-L. mounted on an aluminum plate and grounded to the plate with copper tape. The aluminum plate was connected to real ground and mounted on a screw driven variable speed flat bed carrier which moves at the rate of inch/sec over a positive single wire corotron charged to 4.5 to 6 kV. Fifteen seconds after corona charging the plate with the mounted samples passed over a wave of negatively charged black liquid toner (13) comprising aluminum tristearate adjuvant and Basic Barium Petronate® charge director similar to that described in Assignee's U.S.S.N 857.326 filed April 30, 1986 having a conductivity of 10-15 pmhos/cm and 0.5% solids concentration which formed a meniscus with the sample and deposited toner on the polymerized areas of the samples. After toning, the images were fused in a 105 110 degree centigrade oven for 5 minutes. The results show Sample 1 which was exposed for 1 minute to UV deactivating radiation did not accept any toner. Sample 2 exposed for 1 minute with polymerizing visible light produced a negative image of the Stouffer Target having 6 toned steps (which could be subsequently transferred 14).

Samples 3 and 4, exposed to 1 minute UV radiation followed by 1 and 0.5 minute visible light, respectively produced positive images (which could be subsequently transferred 15) of the Stouffer target having 1 and 3 untoned steps followe 'v completely toned steps.

f Image quality in the negative mode was determined by placing the emulsion side of an UGRA target that included 0.5% highlight dots to 99.5% shadow dots on top of the photopolymerizable layer of a 1 inch x 7 inch (2.54 cm x 17.8 cm) strip of a 41 r 42 photopolymerizable element prepared as described earlier in a Douthitt exposure unit(Douthitt Corp., Detroit, MI), equipped with a Theimer Violux Model TU64a lamp housing and a 5KW. 5027 photopolymer bulb.

drawing vacuum for 60 seconds to obtain good contact between the target and the photopolymerizable layer and exposing the photopolymerizable layer for seconds through a Dylux® Clearing Filter (DCF) sold by E. I. du Pont de Nemours and Company of Wilmington DE. The DCF filtered out radiation shorter than 400 nm. Seven other elements were so exposed with the exposure time varied from 40 to 70 seconds as shown in Table 4 below. The lamp output was measured as 1.41 mw/cm After exposure, the cover sheet was peeled off and the exposed element was charged and toned as described above. The results for the untransferred negative toner image on the master are shown in Table 4.

TABLE 4 Exposure Time Toned Percent (seconds) steps dot range 35 1 3-98 2 3-99 25 45 2 3-99 3 3-99 3 2-99 60 4 2-99 4 2-99 70 4 2-99.5 Excellent quality negative images of 2 to 99% dots were obtained with exposures ranging from 55 to seconds.

Positive images were prepared by imagewise exposing six photopolymerizable elements prepared as 42 ri described earlier to exposures of 10, 20. 30. 40, and 60 seconds, respectively. The exposures were made in a Douthitt exposure device through a KokomoS Glass Filter (400). Kokomo Opalescent Glass Co..

Kokomo. IN. The Kokomo® filter primarily allowed only wavelengths between 300 and 400 nm to pass through it. The lamp output was measured at 1.39 mw/square cm. Again UGRA targets were placed over the photopolymerizable layer of the photopolymerizable element and a 60 second vacuum drawdown time was used for each exposure. After the UV exposure, each sample was given an overall exposure of 55 seconds to visible light through a DCF filter. The cover sheet was peeled off, and the exposed element was charged and toned as described earlier. Results for the untransferred positive toner image on the master are shown in Table TABLE UV Exposure Time (seconds) Untoned Steps Dot Range 0 1-98 1 2-99 30 2 3-99.5 40 3 4-99.5 3 5-99.5 60 4 5-99.5 Excellent quality positive images of 1-98 and 2-99% dots were obtained at 10 and 20 seconds UV exposure followed by an overall 55 second visible exposure.

To study the effect of an exposure time delay between the imagewise UV deactivation exposure and the overall visible polymerization exposure on 43 I

I

44 image quality, the time between the two exposures was varied from 1 to 20 minutes. The image quality obtained was identical for all hold times studied showing good latent image stability of the deactivation species formed during imagewise UV exposure.

A photopolymerizable element similar to that described earlier was imaged for 20 seconds through a Kokomo® Glass filter in a Douthitt exposure unit using a Cromalin® offset com guide positive target, sold by E. I. du Pont de Nemours and Company.

Wilmington. DE. The UV exposure was followed by a an overall visible exposure through a DCF filter for seconds. The cover sheet was peeled off the exposed 15 element, and the element was then charged electrostatically, the resulting electrostatic image was toned with liquid electrostatic toner of opposite polarity, and the toned image was electrostatically transferred from the master to paper. The film was charged with a scorotron having an open grid, spaced mm from the element and operated at 180 V and a Swire operated at 4.8 kV. The element was then toned 1.6 seconds after charging using the black liquid S"electrostatic toner at 1.5% solids concentration described earlier. The excess toner was removed from the element with a metering roll spaced 0.004 inch (0.10 mm) from the element. The metering roll is biased from 0 to 300 V, if necessary, to remove toner from the background non-image areas, and the toner image was transferred to Champion TextwebO paper Champion Paper Co.. Stanford, CT using a combination of a conductive rubber roller, operated at -2 to -6 kV, and a transfer corotron, operated at to +5.5 kV. The paper was placed between the toned element and the conductive rubber roller so the 44 paper was in contact with the toner image. The paper was then passed under the corotron causing the toner image on the element to be transferred to the paper.

The image was then fixed to the paper by fusing at 110 0 C for 1 minute. Solid density was 1.72 measured with a Macbeth Model RD-918 Densitometer from Kollmorgan Corp., Newburgh. NY, and dot gain for dots was 14.9%. A dot range of 2-98% was obtained.

The image was sharp and an excellent reproduction of the positive target.

EXAMPLE 2 A photopolymerizable element was prepared o having a 0.004 inch (0.0102 cm) aluminized a" 15 polyethylene terephthalate support and a 0.00075 inch (0.002 cm) polypropylene cover sheet. The photopolymerizable layer had the following composition: o* i INGREDIENT WEIGHT o-CL HABI 2.17 CDM HABI 2.17 S6-NVA 1.73 2-MBO 0.10 TLA-454 1.48 25 LCV 0.39 DBI 0.65 TMPEOTA 31.06 S*PSMMA 60.25 The coating weight of the photopolymerizable layer was 120 mg/dm 2 Six photopolymerizable -L elements were imagewise exposed for 5, 10. 15, and 60 seconds respectively in a Douthitt exposure unit through a DCF filter. The lamp output 2 was 1.4 mw/cm The cover sheet was peeled off, L j r i 1 -7 and the exposed element was charged and charge/decay data was obtained as described in Example 1. Results are shown in Table 6 below.

TABLE 6 Seconds After Charging 0 60 120 Voltage Retained After 861 485 358 300 222 181 158 99 Visible 1076 1282 798 580 622 453 460 355 249 209 173 150 153 119 118 76 Exposure 1015 1114 741 878 590 729 479 837 282 446 191 337 135 262 51 126 1269 998 892 800 634 529 454 290 1.

i o a.

a o a o 0 a 0 ar 0 00 0 0a 000 0 Exposure 5 10 (Seconds) 15 20 30 The above data shows that visible light caused polymerization to occur and that charge is retained by the polymerized film.

25 Four similarly prepared photopolymerizable elements having a photopolymerizable layer comprising a 6-NVA photoinhibitor and DBI as a visible sensitizer were imagewise exposed in a Douthitt exposure unit through a UV light transmitting.

visible light absorbing Kokomo® Glass Filter for 10. 20. 30. and 60 seconds, respectively. The elements were then given an overall 20 second exposure through a DCF filter. The cover sheets were peeled off, and the elements were charged, toned and charge/decay data were obtained as described in Example 1. Results are shown in Table 7.

46 17t Sample No.

TABLE 7 Secs. After Voltage Retained After Charging Dual Exposure 1 2 3 0 409 54 40 3 118 8 49 4 7 27 3 6 9 2 3 2 3 120 2 0 2 o 00 00 0 0000 1 os ioi 0 0 o o 0 or 00 0 Db Ooo~e 00 o n oa 00 0 006 O 0 0s 0 00 0 60 0 90 Q 00 000 9 0 Q Q The above data show increasing amounts of deactivation by longer exposure to LU radiation in 15 the first exposure which hinders polymerization in the second exposure to visible light.

Image quality in the negative mode was determined by placing the emulsion side of an UGRA target on top of the photopolymerizable element in a Douthitt Option X exposure unit (Douthitt Corporation.

Detroit, MI), equipped with a Theimer Violux Tu64a lamp housing with 5027 photopolymer bulb, drawing vacuum for about 60 seconds to obtain good contact between the target and the photopolymerizable element and exposing the element through a DCF filter. The lamp output was measured at 0.98 mw/cm 2 After exposure the cover sheet was peeled off, and the element was charged electrostatically, the resulting electrostatic image was toned with a liquid electrostatic toner of opposite polarity, and the toner image was electrostatically transferred from the element to the paper using the procedure described in Example 1 with the following exceptions: The grid voltage was set at 260 volts, the corona current, Ic was 550 micro amps, the 47 48 conductive rubber roller was set at -3.5 kV, the transfer corotron was operated at 4 kV, the magenta toner solids concentration) used was similar to that described in Example 10 of Assignee's U.S.S.N.

857.326 filed April 30, 1986 wherein the lecithin charge director was replaced by Basic Barium Petronate,® and the toner has a conductivity of 14 pmhos/cm. The paper used was Solitaire® paper Plainwell Paper Co., Plainwell, MI, and the transferred image was fused at 113 0 C for 1 minute.

Four samples were prepared using exposure energies of 25, 30, and 35 mj/cm 2 Results are shown in Table 8.

TABLE 8 15 Sample No. 1 2 3 4 Exposure Energy (mj/cm 2 20 25 30 Toned Stouffer Steps 2.5 3 3.5 4 Dot Range 2.5-98 2-97 2-97 Dot Gain 14 15 14 Top Density 1.09 1.10 1.37 i Jt Four photopolymerizable elements having the photopolymerizable composition outlined earlier in this example were prepared and image quality of a Stransferred image on paper was determined using different UV exposure conditions for each of these elements. The elements were first exposed imagewise through-an UGRA target and a Kokomos Glass filter, Kokomo Opalescent Glass Co., Kokomo, IN in a Douthitt SOption X exposure unit similar to that described earlier. The lamp output was determined to be mw/cm through the KokomoS Glass filter.

Following the UV exposure, the elements were subjected to a second overall visible exposure 48 through the DCF filter. The cover sheet was peeled off each exposed element, and the elements were charged, toned and the toner image transferred using the method described earlier for determining the image quality in the negative mode with the following exceptions: the grid voltage was maintained at 270 volts instead of 260 volts. Results are shown in Table 9.

TABLE 9 Sample No. 1 2 3 4 UV exposure energy 7.5 10 15 21 2 15 (mj/cm Visible exposure 35 35 35 energy (mj/cm 2 Untoned Stouffer Steps 1 1.5 3 Dot Range 2-97 2-98 4-98 3-98 Dot Gain 14 12 10 9 Top Density 1.28 1.40 1.43 1.37 I This example demonstrates the use of 6-NVA t t 4 It UV generated photoinhibitor and DBI visible photosensitizer in a dual response electrostatic imaging composition useful for making negative and positive images depending on the exposure sequence.

EXAMPLE 3 The procedure used to determine image quality in the negative and positive modes described in Example 2 was repeated with the following exceptions: The photopolymerizable layer had the following composition: 49 1 Bf 5 7

INGREDIENT

o-CL HABI CDM HABI

DHP-M

2-MBO TLA-454 p-TSA

LCV

DABC

ETQC

TMPEOTA

PSMMA

WEIGHT (GMS) 30.4 30.4 55.2 1.4 46.2 46.2 5.46 6.86 6.86 413.4 752.6

I

i g :i i

I

4 *4*9 *49 I IC ~t I I I I Si S ZIS The photopolymerizable layer has a coating weight of 117 mg/cm The toner used had a conductivity of 11 pmhos/cm image quality in the negative mode is shown in Table 10 an that in the positive mode is shown in Table 11.

TABLE Sample No. 1 UV Exposure Time(secs) 10 Exposure Energy(mj/cm 2 17.8 Dot Range 2-98 Dot Gain 7 Top Density 1.14 2 3 15 20 27 36.4 3-98 2-97 8 13 1.49 1.60 4 56 2-97 14 1.64 Excellent image quality of 3-98% dots at a density of 30 1.49 and a dot gain of 8% was achieved in the negative mode with DHP-M in a dual response electrostatic imaging composition.

I

51 TABLE 11 Sample No. 1 2 3 4 UV Exposure Energy(mj/cm 2 5.1 8.5 12.2 18.1 Visible Exposure Energy 28.3 28.3 28.3 28.3 (mj/cm 2 of Untoned Stouffer Steps 1 1.5 2.5 Dot Range 2-97 2-98 4-98 3-99 Dot Gain 12 10 5 Top Density 1.35 1.41 1.31 1.27 Excellent image quality of 2-98% dots at 1.41 density and a dot gain of 10% was achieved in the positive mode with DHP-M. This example shows an electrostatic Simaging composition containing DHP-M works equally S 15 well in producing positive or negative images depending on the exposure sequence.

EXAMPLE 4 SA photopolymerizable element was prepared having a 0.004 inch (0.01 cm) aluminized polyethylene Dterephthalate support and a 0.00075 inch (0.002 cm) polypropylene cover sheet. The photopolymerizable I layer had the following composition: INGREDIENT WEIGHT (GMS) 25 o-CL HABI 30.4 i "CDM HABI 30.4 a-METHYL BPE 41.44 2-MBO 1.4 TLA-454 46.2 p-TSA 46.2 LCV 5.46 DABC 6.86 ETQC 6.86 TMPEOTA 413.4 PSMMA 771.4 2 52 The photopolymerizable layer had a coating 2 weight of 115 mg/dm.

Charge/decay data for the above photopolymerizable element was measured as described in Example 1 and is outlined in Tables 12, and 13 below. Table 12 shows charge retention after exposure to visible light. Table 13 shows charge retention after a dual exposure of UV radiation followed by visible radiation of 20 seconds.

TABLE 12 I t i t Seconds After Charging 0 120 Voltage Retained After Visible Exposure 70 196 425 618 844 971 15 57 182 323 575 781 5 31 117 220 442 672 2 18 82 168 359 595 0 5 35 90 225 450 0 2 22 60 167 363 0 2 14 42 127 307 0 0 3 17 67 193 o oa P e d ~o P D O O O b*I n BbD4U9 B G Visible Exposure 25 (seconds) 5 10 15 20 30 These data show that visible light causes polymerization to occur and that charge is retained in the exposed areas of the polymerized film.

f~il~L~irr* _1 P~ L 53 TABLE 13 Volts Retained Seconds After Charging 0 After Dual Exposure 206 14 79 6 3 44 4 3 28 4 2 11 3 2 4 3 2 UV Exposure (seconds) 10 20 30 Visible Exposure 20 20 20 (seconds) These data show deactivation by UV radiation which prevents polymerization to occur in the UV exposed areas upon exposure to visible radiation.

Image quality was determined as described in Example 2 with the following exceptions: the photopolymerizable element used was the one described earlier in this example. The grid voltage was set at 180 volts and the conductive rubber roller was set at -4kV. Results for the negative mode are shown in Table 14, and results for the positive mode are shown in Table 15 below.

TABLE 14 I d,~i Sample No.

Visible Exposure Energy (mj/cm 2 Toned Stouffer Steps Dot Range Dot Gain Top Density 2 3 26.6 3.5 2-98 12 1.37 37.6 55 4.5 5 2-97 2-97 12 15 1.47 1.54 4 74.7 7 2-96 16 1.55

-I

i t b 54 TABLE Sample No. 1 UV Energy(mj/cm 7 Visible energy(mj/cm 2 35.4 Untoned Stouffer Steps 1 Dot Range 2-97 Dot Gain 12 Top Density 1.41 2 3 11 13.5 35.4 35.4 2 1.5 2-97 2-98 10 7 1.42 1.40 4 22 35.4 2-98 9 1.43 -Itt

I

Ir at

I

I I A 11 zC Excellent exposure latitude is achieved with the a-METHYL BPE photoinhibitor in combination with DABC and ETQC visible sensitizers.

EXAMPLE Image quality for the negative and positive modes were determined as described in Example 4 with the following exceptions: The photopolymerizable layer had the following composition: :i

I

i I 20 INGREDIENT o-CL HABI CDM HABI a-METHYL BPE 2-MBO TLA-454 p-TSA

ETQC

TMPEOTA

PSMMA

WEIGHT (GMS) 15.2 15.2 41 4 14.0 46.2 46.2 6.86 423.8 790.8 The photopolymerizable layer had a coating weight of 123 mg/dm 2 The grid voltage was maintained at 145 volts for the negative mode and 200 volts for the positive I I--IIXL-.X- L~LI-- r^T--Cr U~r- ulmode. Results for the negative mode are provided in Table 16 and results for the positive mode are shown in Table 17 below.

T

Sample No.

Visible Exposure Energy (mj/cm 2 4 Toned Stouffer Steps Dot Range Dot Gain Top Density ABLE 16 1 2 3 4 18.5 28.6 38.5 4.5 5.5 7 2-97 1-96 1-96 12 18 18 1.41 1.45 1.48 54 1-95 21 1.49 ttp I *f

I-

rCi rI 'D I i *f 4

IIIC

CCC'l TABLE 17 SAMPLE No.

UV Exposure Energy(mj/cm 2 Visible energy (mj/cm 2 Untoned Stouffer Steps 20 Dot Range Dot Gain Top Density 1 2 7.5 10.3 37 37 1 1.5 2-97 2-97 21 16 1.53 1.48 3 13.9 37 3 2-98 13 1.47 4 21 37 2-98 12 1.49 Excellent quality positive and negatives 25 were achieved with the imaging composition containing ETQC as the sole visible photosensitizer.

I

Claims (43)

1. A process for producing a negative image from a photohardenable electrostatic master comprising imagewise exposing to visible radiation a photohardenable electrostatic master comprising an electrically conductive substrate bearing a photohardenable layer comprising a polymeric binder, a compound having at least one ethylenically unsaturated group, a photoinitiator, a nitroaromatic photoinhibitor, and at least one visible light sensitizer; exposing at least the unexposed image areas to ultra violet radiation charging electrostatically the photohardenable electrostatic master to form a latent image of electrostatic charge on the imagewise exposed areas; developing the charged latent image by applying an electrostatic toner of opposite charge; and transferring the toned image to a receptor surface.

2. A process according to claim 1 wherein the Sphotohardenable electrostatic master is electrostatically charged by corona discharge.

3. A process according to claim 1 or 2 wherein the electrostatic toner of opposite charge is a dry electrostatic toner.

4. A process according to claim 1 or 2 wherein the electrostatic toner of opposite charge is present in a liquid electrostatic developer. 7r-4 A process according to claim 4 wherein the liquid electrostatic developer comprises a nonpolar liquid having a Kauri-butanol value of less than 30, a thermoplastic resin having an average particle size of less than 10 m, and a nonpolar liquid soluble ionic or zwitterionic compound.

6. A process according to claim 5 wherein the liquid electrostatic developer contains a colorant.

7. A process according to any preceding claim wherein the receptor surface to which the toned image is transferred is paper.

8. A process according to any preceding claim wherein 9 o steps to are repeated at least one time, and the toned "o image is transferred to a different receptor surface. o*

9. A process according to claim 1 wherein steps (A) 5 to are repeated at least one time and the toned image is o o transferred in register to the toned image on the receptor surface. A process according to any one of claims 1 to 7 wherein steps to are repeated four times, the imagewise t exposure being to different photohardenable electrostatic masters through different separation transparencies corresponding to yellow, cyan, magenta and black; the developing (D) 57 i 58 being by means of an electrostatic toner of a color corresponding to that of the transparency, and the transferring of the toned image being in register to the initial toner image on the receptor surface.

11. A process according to claim 10 wherein the receptor surface is paper.

12. A process for producing a positive image from a photohardenable electrostatic master comprising imagewise exposing to ultraviolet radiation a photohardenable electrostatic master comprising (1) SS, an electrically conductive 15 substrate bearing a Sphotohardenable layer comprising a polymeric binder, a compound having at least one ethylenically unsaturated group, a photoinitiator. a/photoinhibitor. and at least one visible light 2 sensitizer; exposing overall the photohardenable electrostatic master to visible radiation: charging electrostatically the photohardenable electrostatic master to form a latent image of electrostatic charge on the imagewise exposed areas; developing the charged latent image by applying an electrostatic toner of opposite charge; and 58 Af. 7 )r transferring the toned image to a receptor surface. I

13. A process according to claim 12 wherein the photohardenable electrostatic master is electrostatically charged by corona discharge.

14. A process according to claim 12 or 13 wherein the electrostatic toner of opposite charge is a dry electrostatic toner. A process according to claim 12 or 13 wherein the electrostatic toner of opposite charge is present in a liquid electrostatic developer. t 9 t -15 U Io *t Witt 9 te 1 2 Is I I 1*04 I I *114 II 20 14

16. A process according to claim 15 wherein the liquid electrostatic developer comprises a nonpolar liquid having a Kauri-butanol value of less than 30, a thermoplastic resin having an average particle size of less than 10 m, and a nonpolar liquid soluble ionic or zwitterionic compound.

17. A process according to claim 16 wherein the liquid electrostatic developer contains a colorant.

18. A process according to any one of claims 12 to 17 wherein the receptor surface to which the toned image is transferred is paper.

19. A process according to any one of claims 12 to 18 wherein steps to are repeated at least one time, and the toned image is transferred to a different receptor support. 59 A process according to claimsl2xwherein steps to are repeated at least one time, and the toned image is transferred in register to the toner image on the receptor surface.

21. A process according to claim 12 wherein steps to are repeated four times, the imagewise exposure being through different separation transparencies corresponding to yellow, cyan, magenta and black; the developing being by means of an electrostatic toner of a color corresponding to that of the transparency, and the transferring of the toner image being in register to the initial toner image on the receptor surface.

22. A process according to claim 21 wherein the receptor surface is paper. t1'

23. A process according toclaimsl wherein compound is a nitroaromatic compound of the formula IR 1 2 S 25 NO 25R3 CHR 5 R 6 R R R and R alike or different are H, OH, halogen, NO 2 CN, alkyl of 1 to 18 carbons, Salkoxy in which the alkyl is of 1 to 18 carbons, acyloxy of 2 to 7 carbons, aryl of 6 to 18 carbons, benzyl. halogen-substituted phenyl, polyether of 2 to 18 carbons and 2 to 61 oxygens, dialkylamino in which each alkyl is of 1 to 18 carbons, thioalkyl in which the alkyl is of 1 to 18 carbons, or thioaryl in which the aryl is of 6 to 18 carbons, R 2 and R 3 taken together are -OCH 0- or -O-4-CH CH 0-4- in which q S2 9 1 2 is an integer from 1 to 5. or any two of R R 2 3 4 R and R taken together are the residue of a second benzene ring fused into the benzene nucleus, with the proviso that not more than one of 1 2 3 4 R R R and R is OH or NO2. R is H. alkyl of 1 to 18 carbons, halogen, phenyl, or alkoxy in which the alkyl is of 1 to 18 t carbons. 6 R is H. OH, alkyl of 1 to 18 carbons, phenyl, alkoxy in which the alkyl is of 1 to 18 carbons, or aryloxy of 6 to 18 carbons unsubstituted or jsubstituted with halogen, alkyl of 1 to 6 carbons, or alkoxy of 1 to 6 carbons, with the proviso that only one of R 5 and R 6 is H. or R and R together are =CH 2 -O-CH 2 =NC6H =NC 6 H 4 N(alkyl) 2 in which each alkyl is of 1 to 18 carbons. -O-C2H4-0-. =N(alkyl) in which the alkyl is of 1 to 6 carbons, R 0 2 N R 2 =N(hydrocarbylene) N=CH R3 R 4 in which the hydrocarbylene group is of 1 to 18 carbons, or 61 62 C C =NH C C 7 8 9 R H R R 8 9 in which R and R alike or different, are H or 7 10 alkyl of 1 to 4 carbons, and R and R alike or 11 11 different, are -CN. -COR 1 in which R is alkyl of 1 to 5 carbons, or -COOR 12 in which R 12 is alkyl of 1 to 6 carbons which may be interrupted by an oxygen atom, alkenyl of 2 to 5 carbons, or 7 8 16 alkynyl of 2 to 5 carbons, or R and R together. 9 10 or R and R 0 together, complete a 6-membered carbocyclic ring containing a keto group.

24. A process according to claim 12 wherein compound is a nitroaromatic compound of the t formula R 1 2 R NO R 3 CHR 5 R 6 R CHR R 4 wherein S1 2 3 4 R R R and R. alike or different are H. OH, halogen. NO CN, alkyl of 1 to 18 carbons. 2 alkoxy in which the alkyl is of 1 to 18 carbons, acyloxy of 2 to 7 carbons, aryl of 6 to 18 carbons, benzyl, halogen-substituted phenyl. polyether of 2 to 18 carbons and 2 to oxygens, dialkylamino in which each alkyl is of 1 to 18 carbons, thioalkyl in which the alkyl is of 1 to 18 carbons, or thioaryl in which the 2 3 aryl is of 6 to 18 carbons. R and R3, taken together are -OCH 2 0- or -O---CH 2 CH 2 in which q 62 i j I 63 is an integer from 1 to 5, or any two of R R 2 3 4 R and R taken together are the residue of a second benzene ring fused into the benzene nucleus, with the proviso that not more than one of R 1 R 2 R and R is OH or NO 2 R is H, alkyl of 1 to 18 carbons, halogen, phenyl, or alkoxy in which the alkyl is of 1 to 18 carbons, R 6 is H, OH, alkyl of 1 to 18 carbons, phenyl, alkoxy in which the alkyl is of 1 to 18 carbons, or aryloxy of 6 to 18 carbons unsubstituted or substituted with halogen, alkyl of 1 to 6 carbons, or alkoxy of 1 to 6 carbons, with the 5 6 proviso that only one of R and is H. or R and R together are =CH 2 -O-CH 2 =NC 6 H 5 =NC 6 H N(alkyl) 2 in which each alkyl is of 1 to 18 carbons, -0-C2H =N(alkyl) in which the alkyl is of 1 to 6 carbons, R 1 0 2 N R 2 =N(hydrocarbylene) N=CH R 3 R4 in which the hydrocarbylene group is of 1 to 18 carbons, or C =C =NH C C- S7 8 R9 8 R9 in which R and R alike or different, are H or 7 10 alkyl of 1 to 4 carbons, and R and R alike or different, are -CN, -COR 11 in which R I is alkyl 63 Ii r. 64 of 1 to 5 carbons, or -COOR 12 in which R 12 is alkyl of 1 to 6 carbons which may be interrupted by an oxygen atom, alkenyl of 2 to 5 carbons, or alkynyl of 2 to 5 carbons, or R 7 and R 8 together. 9 10 or R and R 0 together, complete a 6-mernbered carbocyclic ring containing a keto group. A process according to claim 23 wherein compound is an arylylidene aryl ketone compound of the formulae: 0 R 6 A. o R 1 II R 7 CH-+ CH CH+- N 15 0^ a 0-(U R R I z 2 R 4 R wherein: A, B. D. E are carbon atoms or one may be solely a nitrogen atom; R is H. OH or CH 3 0; R 2 is H. OH. CH 0 or N(R); R is H. OH or CH 0; 3 3 a is 0 or 1; Z is >CHOH. >C(CH 3 2 4 (-CH 2 b. 3 2# 2 b wherein b is 1. 2 or 3. 0 0 CH S CH R 1 R wherein R' is H. phenyl. or Z is linked with R4 where z is 64 1 and R 4is or >N-CH 3 *a being 0; R is H. CH 3-OH, CH R 5is H or R 5+R 7 is -CH 2CH 2- CH 2CH 2C 50 C 2 2 2H 2C-- R 6is H or R 6 +RH is -CH 2CH 2- CH 2CH 2CH 2- O-CH 2CH and R is C (C H2)nCH3where n is 1 to -CH 2 CH 2 -Cl -C 2 CH 2 OH, CH 2GCH OCH3 I. R R 9B. 0 R 1 3 r I H 0 BD AN B-A 6 R 5R 7 R 8 wherein: A. B. D are carbon atoms or one may be solely a nitrogen atom; HR is H. CH. -OCH 2 CH OR. wherein H is H. CH. -CH CHl OR' wherein R' is CH or CH CH 2 2 3 3 2 R is H. CH 3 OH. or CH 0; H 3 is H. OH. CH 3 0. CHl 3 F. Br. CN or R +R is -0-GCl 2 3 2 R 4 is H. CH or CH 3 O0: R 5 is H. CHl 3 -OCH 2 CH 2 OR. wherein R is H. CH 3 -CH CH OR' wherein RI is GCl or CH CH 2 2 3 32' R 6 is H. CH 3 or phenyl; R. is H. CH 3 v OH or CH 3 0: H is H; R +R is -CH -CH2CH 2CH2v 8 10 2 2 222 -OCH 2CH 2; R9 iH.R9 +R10 is-H2 CH2- -C 2 CH 2 CH 2 -s -OCH 2 CH- 2 and I j 66 R 10 is CH V -+4-CH 2 nCH 3 wherein n is 1 to anrd N (R 2 2 or. soon 0 0 060 00&0 00 06000 o3 n of wherein G is or Ris H. CH 3or OC3-and R 2is CH 3or -CH 2 CH V the ketone having its maximum absorption in the range of 350 to 550 rim.

26. A process according to claim 24 wherein compound is an arylylidene aryl ketone compound of the formulae: 0 R 6 roy""*N CH-+ CH CH*-a()N 67 wherein: A. B. D. E are carbon atoms or one may be solely a nitrogen atom; R 1 is H. OH or CH R 2 is H. OH. CH 30 or N(R7)2 R 3 is H. OH or CH 3 0; a is 0 or 1; Z is >CHOH. >C(CH 3 2 (-CH 2 b wherein b is 1. 2 or 3. 0 S- C CH S CH wherein R' is H. phenyl. or Z is linked with R 4 where Z is Ote, 4#00 o. f fWand R 4 is or >N-CH a being 0; R 4 is H. H OH 0 R is H or R +R is -CH 2 CH 2 -CH 2 CH 2 CH 2 -O-CH CH 2 2 2 2R 6 is H or R 6+R 7 is -CH 2 CH 2 -CH 2 CH 2 CH 2 SO-CH 2 CH and R 7 is CH 3 -(CH2)n-CH 3 where n is 1 to -CH 2 CH 2 -C1, -CH 2 CH 2 OH. CH 2 CH 2 OCH R R R 2 1 9 0 R rq/ SR 3 o CH R/ \It R R 7 8 7t 7 67 Ris or is-CH-H-- -CHCH-H-- p C 0D i 68 A' wherein: A, B. D are carbon atoms or one may be solely a nitrogen atom; R 1is H. CM 3 V OCH 2CH 2OR. wherein R i6 H. CH V -CHM CH 2OR' wherein R' is CH 3or CHM CM R 2is H. CH 3- OH. or CH R 3is H. OH. CH 3 0. CH 3 F. Br. Cli or N(R 1 0 2 R 2+R 3is -0-CM R 4is H. CM or CM 0; R 5 is H. CM 3 -OCH 2 CH 2 OR. wherein R is H. CH 3 -CM CM OR' wherein RI is CH 3or CM CH 2- R6is H. CH C 3 or phenyl: R7is H. CH3 OH R is H: 8 R +R is -CM CH CH2CH 2CH 0ft8 10 2 M 2 C is H. 2 +2 i CHC CM CH C 9 9 102 22 2 2 -OCH 2 CMH- and R 10is CM 3 CHM 2 nCM 3 wherein n is 1 to and ~0 R C 0Cli N(R 2 2 or 0 0 R1 300 68 whrein69 wheeinG is or R1is H, CM 3 or -0CM 3 and R 2is CHM o -CH 2 CH V ketone having its maximum absorption in the range of 350 to 550 nm.

27. A process according to claim 23 wherein compound is 1-(2'-nitro-4'.5'-dimethoxy)phenyl-l- (4-t-butyl phenoxy)ethane.

28. A process according to claim 24 wherein compound is 1-(2'-nitro-4'.5'-dimethoxy)phenyl-l- (4-t--butyl phenoxy)ethane.

29. A process according to claim 25 wherein compound is 2 ethyl 3. 4-tetrahydro-6- quinolylidene)-l-chromanone.

30. A process according to claim 26 wherein compound is 2-(N-ethyl-l.2,3.4-tetr-hydro-6- quinolylidene)-l-chromanone.

31. A process according to claim 25 wherein photohardenable electrostatic master comprises an aluminized polyethylene terephthalate support bearing a photohardenable layer wherein binder is poly(styrene/methylmethacrylate). compound is ethoxylated trimethylol propane triacrylate. photoinitiator is the combination of22-bs- chlorophenyl)-4.4'.5.5'-tetraphenylbiimidazole and 2'2'-bis(o-chlorophenyl)-4.4'.5.5'-tetrakis(m- methoXyphenyl)-biimidazole. photoinhibitor is 1.(2'-nitro-4'.5'-dimethoxy)phenyl-1-(4-t-buty1 phenoxy)ethane and visible light s~pnsitizer is 69 ~71' I t I A 008 0 00 a a9 a000 000 00 0000 00006 V 00 00 a 0 2-(N-ethyl-l.2,4-tetrahydro-6-quinolylidene)-- chroma none.

32. A process according to claim 26 wherein photohardenable electrostatic master comprises an aluminized polyethylene terephthalate support bearing a photohardenable layer wherein binder is poly(styrene/methylmethacrylate), compound is ethoxylated trimethyol propane triacrylate. photoinitiator is the combination of 2,21-bis~o- chlorophenyl)-4,41.5,5I-tetraphenylbiimidazole and 212'-bis(o-chlorophenyl)-4.4'.5,5'-tetrakis(m- methoxyphenyl)-biimidazole, photoinhibitor is 1.(2'-nitro-4'.5'-dimethoxy)phenyl-l-(4-t-buty1 phenoxy)ethane and visible light sensitizer is 2-(N-ethyl-l,2,3.4-tetrahydro-6-quinolylidene)-l- chromanone.

33. A process according to claim 25 wherein 20 the photohardenable electrostatic master comprises an aluminized polyethylene terephthalate support bearing a photohardenable layer wherein binder is poly(styrene/methylmethacrylate). compound is ethoxylated trimethylol. propane triacrylate. photoinitiator is 2.21-bis(o-chlorophenyl)- 4,4'.5.5'-tetraphenylbiimidazole. photoinhibitor (d) is 1,(2'-nitro-4'.5'-dimethoxy)phenyl-1-(4-t-butyl ),,henoxy)ethane and visible light sensitizer is 2-(N--ethyl-1.2.3.4-tetrahydro-6--quinolylidene)-l- chromanone.

34. A process according to claim 26 wherein the photohardenable electrostatic master comprises an aluminized polyethylene terephthalate support bearing photohardenable layer wherein binder is 71 poly(styrene/methylmethacrylate), compound is ethoxylated trimethyol propane triacrylate. photoinitiator is 2.2'-bis(o-chlorophenyl)- 4 4 '.5,5'-tetraphenylbiimidazole. photoinhibitor (d) is 1.(2'-nitro-4'.5'-dimethoxy)phenyl-l-(4-t-butyl phenoxy)ethane and visible light sensitizer is 2-(N-ethyl-1.2,3.4-tetrahydro-6-quinolylidene)-l- chromanone.

35. A process according to claim 1 wherein a protective release layer is present on the photohardenable layer which is removed after step

36. A process according to claim 35 wherein 15 the release layer is polyethylene or polypropylene. 6 to t

37. A process according to claim 12 wherein O#tt a protective release layer is present on the photohardenable layer which is removed after step

38. A process according to claim 37 wherein S, the release layer is polyethylene or polypropylene. Stt t

39. A process according to claim 25 wherein photoinitiator is a hexaarylbiimidazole compound. A process according to claim 26 wherein photoinitiator is a hexaarylbiimidazole compound.

41. A process according to claim 39 wherein a chain transfer agent is present.

42. A process according to claim 40 wherein a chain transfer agent is present. 71 i! 7 r_ I c i; I ~l :r i I- i transfer transfer

43. agent

44. agent agent

46. agent A process according to claim is 2-mercaptobenzoxazole. A process according to claim is 2-mercaptobenzoxazole. A process according to claim is 2-mercaptobenzothiazole. A process according to claim is 2-mercaptobenzothiazole. 42 wherein the chain 41 wherein the chain 42 wherein the chain 41 wherein the chain transfer transfer

47. A process according to claim 1 wherein the binder is poly(methylmethacrylate).

48. A process according to claim 12 wherein the binder is poly(methylmethacrylate).

49. A process according to claim 1 wherein the electrically conductive substrate is aluminized polyethylene terephthalate. A process according to claim 12 wherein the S electrically conductive substrate is aluminized polyethylene terephthalate.

51. A process for producing an image substantially as hereinbefore described with reference to any one of the foregoing examples. DATED this 1st day of March, 1990 E. I. DU PONT DE NEMOURS AND COMPANY By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia